The affirmations which the Decree on Ecumenism contains on the Oriental Churches (UR 13-18), namely on their «ecclesial reality», and consequently, on the nature of the dialogue «between Churches», have provided three necessary conditions for the progress of the dialogue: a theological basis, a new psychological atmosphere and a more adequate ecumenical methodology. In this changed context, relations have developed either with the Orthodox Churches of Byzantine tradition or with the pre-Chalcedonian Churches. Such growing developments exist mainly at two levels and under two different forms: a) At the level of fraternal relations, the «dialogue of love» did indeed help towards a better mutual direct knowledge among the Churches in their real contexts. In this way, the theology of «Sister Churches» has been pratically experienced. b) Theological dialogue, made possible through the dialogue of love, has started a Positive approach towards needed clarifications aiming at and progressing to full communion. Classical questions which divide East from West, like the primacy and papal infallibility have not yet been faced. They will be taken up in the next stage of dialogue. And then, in a new climate. Twenty years of dialogue and exchanges have shown the fundamental validity of the orientation given by the Council to relations with the East. Experience has further enriched this orientation with new perspectives and freed it from certain elements too closely linked with the inheritance of the past. Simultaneously, it has given the orientation of dialogue a more close adherence totality and more respect of the slow rhythm of change, implied in a maturing of the conscience of the entire people of God. Dialogue with the East may be indeed slow, but in final analysis substantial and positive (pp. 517-538).